The present invention generally relates to excavating apparatus and, in a preferred embodiment thereof, more particularly provides improved apparatus for removably attaching a wear member, such as an excavating tooth adapter, to the lip portion of an excavating device such as a bucket, dipper or the like.
Large excavating buckets, dippers or the like are typically provided with a series of earth-cutting teeth which are each formed from two primary parts--a relatively large adapter and a relatively small replaceable point. The adapter has a base portion which is connectable to the forward lower lip of the bucket, and a nose portion onto which the tooth point is removably secured by a suitable connecting pin or other connecting structure. Compared to that of the adapter, the useful life of the point is rather short--the adapter typically lasting through five or more point replacements until the tremendous earth forces and abrasion to which the adapter is subjected necessitates its replacement.
Various structures have been previously proposed for removably attaching adapters, and other wear members such as wear shrouds, to excavating lip structures. For example, in U.S. Pat. No. 5,713,145 to Ruvang a wear shroud having a generally C-shaped cross section is removably attached to the front edge of an excavating bucket lip by first placing the front lip edge in the interior of the wear shroud so that the top and bottom legs of the shroud respectively extend along the top and bottom sides of the lip. A rear end portion of the top shroud leg is then removably secured, using a J-bolt inserted into the top leg after the wear shroud is positioned on the bucket lip, to a base structure welded to the top side of the lip. A nut threaded onto the J-bolt at the rear end of the top shroud leg and facing the welded base structure prevents the forward removal of the installed wear shroud from the bucket lip.
While this particular wear member-to-lip attachment system has proven to be well suited for its intended purpose, it has several limitations and disadvantages. For example, the attachment system requires that the adapter portion of each adapter/tooth point assembly have a relatively high frontal projection area which increases the resistance to penetration of the adapter/tooth point assembly into the material being excavated. Additionally, the adapter-to-lip attachment structure is exposed to the material being excavated, and is thus subject to undesirable abrasion wear. Additionally, the rear portion of the installed adapter tends to promote excavated material "build-up" thereon which, in turn, undesirably decreases the available excavating payload of the bucket.
From the foregoing it can readily be seen that a need exists for improved wear member-to-excavating lip attachment apparatus which will eliminate or at least substantially reduce these limitations and disadvantages. It is to this need that the present invention is directed.